L's and R's

I find Maggie and Kate playing with a bunch of small toys and wagon on the steps.

Me, upon finding Maggie and Kate playing with a myriad of small toys on the steps: "What are you doing?"

Maggie, matter-of-factly: "We're playing caw and sweep."

Me: "Caw and sweep?"

Mag: "Caw and sweep!"

Me: "Call and sweep?"

Mag: "Caw and sweep!"

Me: "Car and sweep?"

Mag: "Caw and sweep. And SWEEP!!"

Me: "Oh...car and sleep?"

Mag: "Yes."

Somehow I'm still a little lost.